The main objective of this study is to compare the albumin turnover rate, distribution and external loss in a group of hemodialysis patients who are participating in the MMHD study funded by the NIH. We will establish baseline plasma albumin concentration and turnover rate, nutritional status, the levels of acute phase proteins in plasma and plasma albumin concentration for a period of 2 years and repeat measurements of albumin turnover either at the end of the 2 year period or following a change in plasma albumin concentration of 4 mg/ml or more.